Biotinylated Fc epsilon RI alpha His&Avi Tag Protein, Human

Fc epsilon RI alpha (FcεRIα) is the α subunit of the high-affinity IgE receptor (FcεRI), whose extracellular region contains two tandem immunoglobulin-like (Ig-like) domains that recognize the Cε3 and Cε4 domains of the IgE Fc segment to achieve picomolar-level (~10⁻¹⁰ M) high-affinity binding, making it the only subunit in the tetrameric receptor complex that directly binds IgE. As the core molecular switch of type I hypersensitivity reactions, FcεRIα is primarily expressed on the surface of mast cells and basophils, functioning to capture and bind IgE antibodies. When multivalent antigens crosslink adjacent IgE molecules, FcεRI clustering is triggered, activating Syk kinase and downstream signaling cascades through ITAM motifs, leading to cell degranulation and the release of histamine, leukotrienes, and other inflammatory mediators that elicit immediate hypersensitivity reactions. Clinically, FcεRIα expression levels positively correlate with disease severity in allergic conditions such as asthma, allergic rhinitis, and atopic dermatitis, while its genetic polymorphisms influence individual susceptibility to allergies. Monoclonal antibodies targeting this pathway (e.g., omalizumab) that block IgE binding to FcεRIα have become the standard treatment for moderate-to-severe allergic diseases, and antibody therapies targeting FcεRIα itself (e.g., CRA2) and humanized antibodies are also under development, providing important strategies for precision anti-allergic therapy.